Special Reactions and Properties of Selected Transition Elements

Vanadium (V)
Oxidation states:  +5, +4, +3 and +2
Vanadium is usually found in ammonium metavanadate, NH4VO3. This is dissolved in sodium hydroxide solution (as it is not very soluble in water), and the solution can be reduced using zinc and an acid. The main ion present is VO2+, called the dioxovanadium(V) ion. V is reduced from +5 to +4.

Chromium (Cr)
Oxidation states: +6, +5, +4, +3, +2, +1, -1, -2
The simplest ion that chromium forms in solution is the hexaaquachromium(III) ion - [Cr(H2O)6]3+. It is fairly acidic and reacts with water in solution, where a hydrogen ion is lost from one of the ligand water molecules - it is acting as an acid.

Manganese (Mn)
Oxidation states: +2, +3, +4, +6 and +7
The simplest ion that manganese forms in solution is the hexaaquamanganese(II) ion - [Mn(H2O)6]2+. Hydroxide ions remove hydrogen ions from the water ligands attached to the manganese ion.
Ammonia acts as a base and removes hydrogen ions from the aqua complex.

Paramagnetism and Diamagnetism

Paramagnetism
Paramagnetism causes the substance to be attracted into the inducing magnetic field.

Paramagnetism is associated with unpaired electrons.
Any substance that has both paired and unpaired electrons will exhibit a net paramagnetism.

Diamagnetism
Diamagnetism causes the substance to be repelled into the inducing magnetic field.

Diamagnetism is associated with paired electrons.